IT IS SUNNAH to pronounce takbīr when starting to rise, and to prolong the takbīr until sitting upright. We have previously explained the number of takbīrāt, the difference of opinion about prolonging it, and the kind of prolongation which nullifies it. When one has completed the takbīr and sits up straight, it is Sunnah to make du‘ā’.
We relate in the Sunans of Abū Dāwūd, at-Tirmidhī, an-Nasā’ī and al-Bayhaqī, as well as others, that Ḥudhayfah 
, in the hadith cited earlier, described the long ṣalāh of the Messenger of Allah 
in which he recited the Sūrahs al-Baqarah, an-Nisā’ and Āl ‘Imrān and in which his rukū‘ and his sujūd were as long as the time he spent standing. He said between the two prostrations: “Lord forgive me, Lord forgive me”, and he sat for as long as his sujūd. [1].
, in the hadith cited earlier, described the long ṣalāh of the Messenger of Allah in which he recited the Sūrahs al-Baqarah, an-Nisā’ and Āl ‘Imrān and in which his rukū‘ and his sujūd were as long as the time he spent standing. He said between the two prostrations: “Lord forgive me, Lord forgive me”, and he sat for as long as his sujūd. [1].
Rabbi-ghfir lī, Rabbi-ghfir lī.
We relate in the Sunan of al-Bayhaqī that Ibn ‘Abbās narrated the hadith about spending the night with his maternal aunt Maymūnah 
and the ṣalāh of the Messenger of Allah at night. [Ibn ‘Abbās] recounted that when he lifted his head from sujūd he said: “Lord, forgive me, have mercy on me, be charitable to me, elevate me, sustain me and guide me.” [2].
narrated the hadith about spending the night with his maternal aunt Maymūnah and the ṣalāh of the Messenger of Allah at night. [Ibn ‘Abbās] recounted that when he lifted his head from sujūd he said: “Lord, forgive me, have mercy on me, be charitable to me, elevate me, sustain me and guide me.” [2].
Rabbi-ghfir lī, wa-rḥamnī, wa-jburnī, wa-rfa‘nī, wa-rzuqnī, wa-hdinī.
According to a report by Abū Dāwūd he added: “And grant me health and well-being”; and the isnād is ḥasan. And Allah knows best.
Wa ‘āfinī.
When performing the second sujūd, the worshipper should say whatever he said in the first. When he lifts his head he should rise pronouncing takbīr and sit in a relaxed position, coming to a complete stop. Then he should stand up for the second rak‘ah and prolong the takbīr in which he rises from sujūd until he stands upright. The prolongation should be after the lām in Allah. This is the most correct of views from our [Shāfi‘ī] colleagues. They also have another view, which is that one should raise one’s head without making takbīr sitting in the istirāḥah position so that as he begins to rise, he pronounces the takbīr. A third view is that one should rise from sujūd saying takbīr so that when he sits, he stops the takbīr and then rises without saying takbīr. It makes no difference if one does not complete two takbīrs in this position. Our colleagues say that the first view is the most correct, so that no part of the prayer is forgotten.
Know that sitting in repose during ṣalāh is a Sunnah established from the practices of the Messenger of Allah in the Ṣaḥīḥ of al-Bukhārī and others. Our doctrine is that it is mustaḥabb because of this authentic Sunnah. Then it is Sunnah after the second sujūd of every rak‘ah after which one stands up. It is not mustaḥabb after the sujūd of recitation in ṣalāh. [3].And Allah knows best.
in the Ṣaḥīḥ of al-Bukhārī and others. Our doctrine is that it is mustaḥabb because of this authentic Sunnah. Then it is Sunnah after the second sujūd of every rak‘ah after which one stands up. It is not mustaḥabb after the sujūd of recitation in ṣalāh. [3].And Allah knows best.References
[1] Muslim (772), Abū Dāwūd (871), and an-Nasā’ī (3/226).
[2] Sunan al-Bayhaqī (2/122).
[3] In one of the manuscripts of the Adhkār of Imam an-Nawawī it states: “I have also explained this in Sharḥ al-Muhadhdhab and Sharḥ al-Bukhārī. My intention in [writing] this book is to mention only specific adhkār.” The commentary on the Ṣaḥīḥ of al-Bukhārī which Imam an-Nawawī refers to was started by him, but he passed away before he could complete it.